Surface-enhanced Raman scattering (SERS) technique is an important and powerful analytical tool, which has attracted much attention for environmental monitoring, chemical analysis and biomedical research. In this paper, we develop a facile method to fabricate the silver-carbon nanocomposites (Ag/CSs) and gold-carbon nanocomposites (Au/CSs). The composites were prepared by one-step hydrothermal reduction method using trioctylamine (TOA) as the soft template and extractant. According to the different amount of TOA added, we prepared a different morphology of the composite material. When the amount of TOA is 1.0 mL, the core-shell composite was obtained. The shape of the silver core shows the hexagon shape and we consider that TOA and glucose selectively adsorb the Ag (111) crystal face resulting in this growth pattern of the silver core. The hydrothermal carbon shell not only effectively avoids the agglomeration of nanoparticles core, but also serves as a protective layer of the SERS active nanostructure during the whole course of the experiment. The detection limit of Ag/CSs for CV molecules up to 10−9 M. The results show that the as-obtained Ag/CSs hold tremendous potential for SERS applications for its long-term stability and superior SERS performance.